Some do it as their contribution to correcting the "social injustices" in the world, because in their minds the software companies are making too much profit.
Some do it because they believe that the world will be a better place if something that can be replicated and distributed without cost to the company, should be offered up for free to everyone.
China cracks software because the business culture of China really is to lie, cheat, and steal, or else cease to be competitive.
Then many do it for profits themselves. File sharing is money. Crack the software, or redistribute the software, and make a few bucks on ad sales on the website. It's piddly money to us here, but even an mere $10/week extra to someone in a poverty-stricken nation is huge.
Most people who crack software live in poor nations, not in the U.S.